The change leaves many developers looking for an alternative. Jim Payne, boss of MoPub mobile ads platform said: "The UDID is essential for managing the conversion loop. All the performance dollars that are spent on mobile are going to impacted by this not being there."

Appsfire is pushing an open-source solution called OpenUDID, though another option is that users could end up being asked for permission to use their UDIDs as Android and Facebook users are when installing a new app.